Apparatus for aerating sewage.



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APPARATUS F08 AERAIING SEWAGE. APrucAnoA msu Asnza. vals.

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pecication of Lettera Patent.

ros ron aanname snwnan ,Patented Dec.. d, wld.;

application led August 2B, 19156. serial Ito. 117,869.

State of California, have invented a new and useful Apparatus forAerating Sewage, of which the following is a specification.

My invention relates to sewage purication, and particularly to thetreatment of sewage by the use of bacteria.

This application is a continuation inpart of application Serial No; 67,667 {iled bv me on December, 18th, .1915.

.Chemically considered sewage is a mixture of hydrocarbons with water,this mixture carrying nitrogen, sulfur, and other compounds partiallydecomposed in suspension and solution. Bacteria multiply in sewae andcause certain chemical and .physical anges 'to occur. 'lhese bacteriamay be classed as aerobic, facultative aerobic, facultative anaerobicand anaerobic. The aerobes can only exist in the presence of free oxygenof the ,air-,.and the anaerobes cannot exist-in the presence of free oxyen. lhe facultative bacteria can -exist w ere free oxygen is present or.absent, but becomes more or less active as the oxygen conditions becomemoreor less favorable. 'Klhe anaerobes which are more active when freeoxygen is absent, cause putrefaction by ex tracting a certain amount ofoxygen from' the compound of the sewage, the products of thisputrefactionbeing ammonia, h drocarbon compounds, hydrogen, and car onsulds, and the like, these compounds being all more or less injuriousand objectionable, and all containingvery little oxygen.' When a sucientquantity of oxygen 1sA supplied to the sewage the aerobic andfacultative aerobic and anaerobic bacteria become active and the sewageis oxidized forming stable. and unobjcctionable compounds.

The rincipal object of the invention is to provide means for treatingsewage, utilizing aerobic and facultative bacteria for this purpose.

'llo accomplish such treatment ll provide means for-.supplying sewagecontaining anabundance of `oxygen to a bacterial culture consisting ofsewage sludge in which the facultative bacteria have been allowed todevelop. l lind, however, that where such a culture is used for longperiods to treat large amounts of sewage that the culture becomes weekand inecient, and that it must then be allowed.) to stand for a'fcertainlength of time under anaerobic conditions and then be aerated so thatthe bacteria may be again properly developed.

ln the use of bacteria for the above pur- 4 poses it is' 4commonpractice to rovide a tankin which the culture is place and into l whichthe sewage is run, this tank having air forced throughit to supply-thefaculta-- tive bacteria with the necessary oxygen to edect anoxidization of the sewage. The ediciency of the method depends on A.thencnessjof the air bubbles supplied, 'and vari ous means have beendevelopedto nely divide the` air and distribute'it through the mass ofsewage.'

The principal object ofiny invention is to culture. By producing amechanical foam"4 t@ composed of sewage 4and air, the air. y broken upinto a multitudeof ne bubbles rovide a new and improved means for ydividing the air and'mi'xing it with the sewlh age to be treated. This l`accomplish. by

so that the maximum of eciency is'ob'- tained. ,'llhisfoam ll-'forin bymechanicallyl mixing air with the sewage by means of ro@ at f tatingpaddles. ,'lhese paddles serve'l to mechanically break up the sewageand'tomix therewith the fine air bubbles.

ln my application Serial No. 67,66Thled 'I December lth, 1915-, lldisclosed a general ,system of treatment in whidh foam prod ucing meanswere used. lin tlie former application foam producing means were,however, located outside the :tank and ll found that the method wassomewhat inecient rdue to the separation of the air into large massesbefore itentered the treating tank.'

A'further objectof the prepent invention is to provide means to mix theair and sewage in the extreme bottom of the treatment tank and toimmediately thereafterP expel the foam so formed into the contents ofthe tank. Referring to the drawings which are for illustrative purposesFigure l is a somewhat diagrammatic view partly in section o f atreating tank embodying my invention. Y

lFig. 2 is an elevation on a large scale of the apparatus located in thecenter of the tank in Fig. l, a portion of this apparatus being brokenaway tobetter illustrate the invention.

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Fig. 3 is a plan view on a plane represented by the line X3- s of Fig.2, this plane being viewed in the direction of the arrows. In the formof my invention illustrated in the drawing a tank 11 is provided, thistank having a sewage inlet channel 12, a liquid outlet channel 13, and asludge discharge pipe 14. A concrete beam 15 extends across the centerof the tank above the level of the liquid therein and serves to supportthe mixing column 16. The mixing column 16 consists of a stationaryshell 20 which is secured to a ange 21 carried in the concrete beam 15and which is provided on its lower end with a collar 22,

this collar being somewhat smaller in diameter than the main portion ofthe shell 20 and fitting tightly around the downlow pipe 23. Secured inthe lower portion of the stationary shell 20 is a sewage supply pipe 24,this pipe being bent down as shown at 25 in Fig. 1 to form a seal andthen extending upwardly and connecting with the channel 12. A liquidintake pipe 30 is connected into the stationaryl shell 20 opposite thepipe 24, the opening 31 between the shell 20 and the intake pipe 30being partially or wholly closed by means of a gate 32 provided with anoperating stem 33.

An overflow we ir 34 is secured to the stationary shell 20 above thepipes 24 and 30, and is connected through a discharge pipe 35 with theliquid outlet channel 13. A cover 40 is tightly secured to `the fiange21 preferably by bolts, the stem 33 projecting through the cover 40 asshown in Fig. 2. An 'air supply pipe 41 also projects through the cover40 extending downwardly inside the downlow pipe 23. The air supply pipe41 may be supplied with compressed air through a compressed air supplypipe 42 the liow of compressed air through this pipe being regulated bya valve 43. The length of the pipe 41 depends on conditions. Under someconditions the valve 43 may be closed and atmospheric air may beadmitted to the air supply pipe 41 through an air intake in an airintake valve 45. When compressed air is being used the valve 45 isclosed. A pipe 46having a valve 47 is secured in the cover 40.

Extending downwardly through a stuifing box 51 in the cover 40 is acentral shaft 50, this shaft being made of considerable diameter toprovide the necessary stiffness and being made hollow to reduce itsweight.

Secured to the lower end of the central pipe 14 and serving to provide abearing for the steady bearing shaft .57 as well as to close the upperend of the sludge discharge pipe 14. Rigidly secured in the upper end ofthe central shaft 50 is a hand wheel 70, this hand wheel being threadedto receive a driving shaft 71, the driving shaft having a head 72. Thedirection of rotation of the impeller 56 being righthanded and thethreads on the shaft 51 being left handed it is obvious that when thehand wheel is jammed down against the head 72 that the shaft 71 and theshaft 50 will be solidly locked together. Shaft 71 is driven throughbevel gear 73 and 74 from a shaft 75 which may be driven from anyconvenient source of power. The method of operation is as follows: Thetank 11 being filledv with sewage in which bacteria have previously beendeveloped, additional sewage is allowed to flow through the channel 12passing through the seal 25 and the sewage supply pipe 24 to thestationaryshell 20, the parts being located as shown in Fig. 2. f Thesewage flows downwardly through thedownlow pipe 23. The impeller 56serves to intimately mix air furnished by the air supply pipe 41 withthe sewage to form afoam 1n which -the air is present in the form ofline bubbles. These bubbles are thrown out from the 'periphery of theimpeller 56 and are widely and uniformly distributed through thecontents of the tank 11 as they rise from the bottom thereof. These airbubbles furnish the oxygen which is necessary for the propagation andsupport of the bacteria. Under some conditionsit is necessary' to supplycompressed air through the air supply pipe 41. In this case the valve 45is closed and the valve 43 is opened, but by running the impeller 52 ata proper speed it creates suilicient suction to operate on atmosphericair, if desired the valve 47 may be opened thus admitting air to the topof the pipe 20, or the valve 43 is closed and the valve 45 is opened,thus admitting air through'the ipe 41. If desired, liquid may be admitteto the downflow pipe 23 by raising the gate 32, this liquid being takenin through the liquid intake pipe 30.

A flow of liquid through the opening 31 is necessary when the flow ofsewage through the pipe 24 is small. Unless a certain quantity of liquidis supplied to the pipe 24 sufficient air is not drawn down by thefalling column of liquid to produce the desired If at any time it isdesired to discharge the contents of the tank 11, this may 'be done asfollows:

'The motion of the shaft 75 is stopped and the hand wheel 70 is thenrotated in such a manner as to lift the pipe 50 on the shaft 71 due tothe screw threads thereon. This lifts the impeller 52, the downflow pipe23 sliding in the collar 22. The toot valve 60 is also lifted, thusopening the sludge discharge pipe 14 and allowing the material in thetank to discharge therethrough.

When the apparatus is operating with a supply of compressed air flowingthrough the pipe 4L the valves 45 and 47 being closed and the valve 43being open, there will be some pressure in the space above the liquid inthe shell 20. .lf this pressure increases abnormally it relieves itselfthrough the pipe 30 rather than to blow back through the sewage in thepipe 25. To prevent the air from thus blowing back the seal isprov-ided, the depth of this seal below the surface of the contents ofthe tank being considerably greaterthan the depth of the bend of thepipe 30. l

ln the practical operation of my invention a supply of sewage sludge inthe tank 1l is first thoroughly aerated for a considerable periodby-opening the gate 32 and ,to warrant starting the sewage through thetank, no sewage being allowed to flow during the preparatory period.During the sewage treatment period the sewage .vith

or without liquid from' the pipe 30 is mixed with air in the impellcr 52in such a manner as to form a foam, the fine air bubbles of which arethrown out into the sewage in the tank 11 thus thoroughly aerating itand supplying the bacteria with the oxygen necessary for their function.

By placing the impeller in the bottom of the tank,.forming the foamtherein and immediately throwing this foam out into the tank the fineair bubbles do not have an opportunity to unite but rise through theliquid in the tank 1l in the form of minute bubbles which have a largecontact surface in proportion to their volume and are thus very ecient.

ll' claim as my invention 1. ln an apparatus for treating sewage, a

foam chamber, means for lntroducing sewage into said chamber, and paddlemeans in said chamber for churning air into said sewage to form a foam.

2. Aln an apparatus for treating sewage; a tank; pipe means for .passingair into the sewage in said tank; and a power driven mixing means forfinely subdividing said air to form a foam.

3. in an apparatus for treating sewage a tank; a downow pipe for passinga mixture of sewage and air to the bottom of said tank; and a powerdriven ilnpeller for breaking up said mixture of sewage and air to forma fokam and for expelling said foam into said tan i In testimonywhereof, ll have hereunto set 1-1y hand at Los Angeles, California, this21st-day of August, 1916.

ALBERT M. BRUSIUS.

